This invention relates to heating and cooling devices, and more particularly it is concerned with a heating and cooling device for an agitator tank serving as a fermentor in which pipe blocks of the vertical trombone type are connected to the inner wall surface of the agitator tank so that they are disposed radially in the tank to effect heating and cooling of the content of the tank.
In heating or cooling the content of an agitator tank, it has hitherto been customary to be done by use of a heating and cooling device which is arranged on the outside of the agitator tank to act on the content thereof from outside, or a device which is arranged within the inside of the agitator tank to act on the content thereof from inside. Sometimes, these two devices have been employed simultaneously. In heating or cooling an agitator tank of a high capacity, for example, the use of a jacket shell alone which is mounted on the outside of the agitator tank is not enough to provide a sufficiently large heat transfer surface area to heat or cool the content of the tank satisfactorily. It is thus usual practice to use, in combination with the jacket shell, a ring-shaped coil which is mounted concentrically with the wall of the agitator tank.
The heating and cooling devices of the prior art mounted in an agitator tank have been unable to achieve satisfactory results in heating or cooling the content of the tank to permit such device to be employed for practical use because of the fact that the heat transfer surface is too small in area to have effect in transferring heat and for other reasons. The piping of such heating and cooling devices is so complex that difficulty is experienced in thoroughly cleaning the interior of the tank, thereby causing the accumulation of saprophytes in the tank.
In the case of a heating and cooling device in which a ring-shaped coil is disposed in the agitator tank or snaked pipes are arranged to form walls arranged in square form along the wall of the tank, the interior of the tank is separated by the heating and cooling device into different zones, so that satisfactory results cannot be achieved in agitating the liquid in the tank. In one type of heating and cooling device known in the art, the straight pipes of the vertical type disposed in the aagitator tank are joined by welding to the wall of the tank because dissimilar materials are used for the pipes and tank. The difference in the materials used results in the difference in thermal expansion between them, so that thermal stresses applied to the materials are increased and there are the possibilities of fractures in the welds of the pipes in service.